Measuring system



Aug. 7; 1928.

" H. M. BAscOM MESURING SYSTEM Filed Aug, 10,. 1927 x IN1/EN TOR. asw/m/ A TTORNEY Patented Aug. 7, 1928.

UNITED STATES PATENT` OFFICE.

HENRY M. BASCOM, 0F BROOKLYN, NEW YORK, ASSIGNOR TO AMERICAN TELE- PHONE .AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.-

MEASURING SYSTEM.

Application filed August 10, 1927.

This invention relates to telephone systems in which it is desired to meter the service by recording the length of time the subscribers telephone is in use.

In such systems, it has been proposed .to operate a metering device periodically by reversing the polarity of the source of energy used for the talking connection. It is the object of the present invention to provide a simple and inexpensive mechanism for reversing the current in such a system, and to this end to provide a simple reversing switch and filter elements for preventing the line from picking up noise due to the comparatively sudden make and break of the reversing switch.

The drawing illustrates diagrammatically a circuit illustrating the invention.

In t-he drawing, two subscribers stations are illustiated,-one at the left and one at the right of the'figure, as illustrated therein, with a subscribers loop extending to the central ofiice' and terminating in the jack 5. Each subscribers loop contains a polarized meter which may be located on the subscribers premises and which will respond to reversals of current on the subscribers loop. A cord circuit ot the central station is indicated at 6 and is here shown as the impedance feed type. A cord circuit ot the repeating coil feed type may be used if desired. In the cord circuit shown, battery is supplied through impedance coils 7,`with capacities 8 connected across their terminals. On one side, the cord circuit is connected to the battery 9. On the other side, the cord circuit is connected to the battery through the reversing switch 11 and the filtering device 12. The switch may be of any desired and known form of simple reversing switch and is here illustrated as operated by a magnet 18 whose circuit is intermittently closed and opened by a commutator 13 operated by any convenient device such as t-he clock mechanism 14. The commutator may be arranged to alternately open and close the circuit of the magnet 18 at any desired intervals, as, for example, every lifteen seconds. Between the reversing switch and the conductors of the cord circuit are connected choke coils 15 Serial No. 212,099.

in series with the leads and a large capacity 16 connected across the leads. A more elaborate filtering arangement may be provided, if desired, but these elements constitute in effect a low-pass iilter which serves to prevent all frequencies above a limit of say 40 cycles per second, which are incident to the sudden opening and closing of the reversing switch, from getting on to the talking conductors of the connection. The capacity 16 may conveniently be of the electrolytic type giving a large capacity in a small compass.

As above pointed out, the reversing mechanism is shown on one side of the cord circuit only, since, in general, it is desirable to charge the call to the calling subscriber only. It will be obvious, however, that the same mechanism could be applied on both sides of the cord circuit, if desired. The reversing switch and iilter elements, which are shown to the lett-of the dotted line 16, may be common to all of the cords of a given exchange, or to a groupy of cords, or, of course, it desired, may be supplied for each cord separately.

lVhile I have illustrated the invention in connection with a typical cord circuit used in manual operation, it will be evident that the invention is equally applicable to machine switching apparatus.

V'Vhat is claimed is:

1. In a telephone system, a central oilice, subscribers stations adapted to be connected thereto, polarized metering apparatus located at the subscribers stations, connect-ing circuits and a source of direct current energy at the central oilice, a switch for reversing the connections ot said current source to one end or" the connecting circuits at regular intervals at a frequency below audibility, choke coils located in the leads between said reversing switch and said connecting circuits, and a capacity connected across said leads adjacent said choke coils.y

Q. In a telephone system, a central oiiice. subscribers stations adapted to be connected thereto, connectingl circuits at said central oflice, polarized metering apparatus adapted to register the period of use of the subscribversing switch from reaching said connecting clrcults.

In tcstnnony whereof, I have signed my 10 name to this specification this I1th day of August 1927.

HENRY M. BASCOM. 

